Exam 1.4: Principles of Radiography and Definitions Flashcards Preview

D2: 621 Radiology > Exam 1.4: Principles of Radiography and Definitions > Flashcards

Flashcards in Exam 1.4: Principles of Radiography and Definitions Deck (56)
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1

Physical properties of x-rays

Weightless and undetectable by human senses

2

What is notable about how x-rays travel?

Travel in straight lines
Cannot be focused on a convergent point

3

What allows x-rays to penetrate our tissues?

Short wavelength

4

What is the difference between diagnostic and therapeutic radiation?

Therapeutic radiation causes a biological change

5

What is the tube made up inside the tube head?

Pyrex glass

6

What is inside the pyrex glass tube

Two electrodes

Also, no air....vacuum tube

7

What is the negative electrode called

Cathode

8

What is the function of the cathode?

It is the source of electrons

9

What is the cathode made of

Tungsten filament wound up inside a Molybdenum cup

10

Is the cathode stronger when it is thick or thin?

Thin

11

How does the cathode "release" electrons

The cathode has a very high melting point, when heated the electrons boil off

12

What is the name of the positive electrode?

Anode

13

What is the function of the anode

It is the target of the electrons released by cathode. It releases the radiation

14

What is the anode made from

copper with a tungsten target

15

What percent of the energy produced by the anode is immediately lost as heat?

99%

16

What happens to the x-ray's energy when it scatters?

It is lowered

17

What does scatter cause in terms of image errors?

Fog

18

What is dangerous about scatter?

It is a source of patient exposure

19

What does it mean when the x-ray is attenuated?

It has been absorbed by the tissue

20

What values are important when trying to determine if an x-ray will be attenuated?

Wavelength
Tissue thickness
Atomic number
Density

21

What is removed from the beam as it passes through, and is attenuated by tissue?

Photons

22

What is the result of attenuation on the image?

Radiopacity

23

What are the two most attenuating tissues in the body?

Enamel and Cortical Bone

24

What results in complete attenuation of x-rays?

Metal restorations

25

In a BW, what percent of x-rays pass through the tissue completely (transmitted) without any interaction at all?

9%

26

If you want to increase the amount of x-rays in the beam (Cross sectional Density/Flux) what adjustment would you make to the machine?

Increase mA

27

What value dictates the penetrating power of the beam?

kVp

28

What is the primary safety feature of well designed x-ray systems?

Dead man switch

29

What is the inverse square law?

Intensity (I) = 1/d^2

30

What is the general idea of the inverse square law?

Intensity of radiation varies inversely with the square of the Source-Film Distance